Use of forced air systems for home heating is well known. A network of ducts is used to carry warm air throughout the home and to return cool air to the furnace for reheating. Since cool air holds less moisture than warm air, household air that comes in contact with cool surfaces, such as windows, tends to condense some of the moisture, leaving the air dry. Dry air allows static electricity to build up, causing the familiar spark when people or pets touch conductive surfaces. If the dryness continues, moisture is drawn into the air from the skin and mucous membranes of the inhabitants or from wood products.
Adding moisture to the air with a humidifier is a well-known method of preventing dry skin, cracking and drying of furniture, as well as making the environment more comfortable. Many types of humidifiers are known, including portable humidifier units and humidifiers that are mounted to hot air furnaces.
Humidifiers for hot air furnaces and space heating systems are typically comprised of a housing having an air inlet and an air outlet for passing space heating air from the furnace through the housing and over and/or through a water fed filter wick in the housing for moistening the heating air passing through the housing and to the space heating system. Portable humidifier units operate substantially the same way using a fan to draw the air through the moistened filter wick and the humidified air being emitted directly to the ambient. In a typical humidifier, water for absorption by the filter wick is held in a reservoir that rests on the base of the humidifier housing. The structure, mode of operation, and beneficial effects of both hot air furnace humidifiers and portable units are well known.
With evaporative humidifiers, if there are any impurities in the water, the contents of the water are wicked up and evaporated along into the air with the water. For example, many municipalities use chlorine to treat the drinking water. The addition of chlorine to disinfect water may be accomplished by chlorine gas (Cl2), sodium hypochlorite solution (NaOCl), chloramine (NH2Cl), or calcium hypochlorite, (Ca(OCl)2). If the treated water is used in the reservoir of the humidifier, the various chlorine species used to treat the water, or byproducts of the chlorine species, such as hypochlorous acid (HOCl), will be carried in the humidified air as it is evaporated into the air with the water. For this reason, it is often recommended to use distilled water in humidifiers. However, it is often inconvenient and more expensive to use distilled water in humidifiers.
Therefore there remains a need for a more convenient way to obtain the benefits of the evaporative humidifiers without evaporating the chlorine species into the air with the water vapor.